1. Field of the Invention
This invention relates in general to hoses of the type used to transport potable water and more particularly to a novel kink-resistant potable water hose with a polyfluorocarbon liner.
2. Description of the Prior Art
Hoses which use silicone or vinyl as the inner tube material have been found unsuitable in many potable water uses because the water carried therein can attain high levels of chlorine. These high levels of chlorine added to the potable water may leach compounds and elements from the tube material. The increased chlorine and leached material often causes the water to be unpalatable. In addition, in the case of a silicone inner tube, a residue of the silicone can cause an oil-like residue on the surface of hot drinks. This is also unappetizing and unappealing. Accordingly, while silicone and vinyl tube constructions provide strength and flexibility, their use as a conduit is aesthetically unsatisfactory in many potable water uses.
Potable water lines which use an inner tube made from a polyfluorocarbon such as polytetrafluoroethylene (PTFE) do not affect the taste of the water. PTFE is an inert material and provides a means of transporting both hot and cold potable water without degrading the taste. However, potable water lines made with a PTFE inner tube have, heretofore, been difficult to install or service due to kinking or collapsing in bending. This is especially true where small bend radius tubing is needed for the potable water application. For example, in potable water lines used in commercial aircraft, it is desirable to have a small bend radius and this exacerbates the kinking and bending problem present in prior art PTFE potable water lines.
The conventional means for resolving a kinking, bending problem in hose is to increase the thickness of the tubing or to add a helically wound reinforcement wire. However, this has not been possible in PTFE tubing of the prior art since increasing the thickness of the PTFE inner tube makes the tube more rigid and less able to meet the bend radius requirements. A thicker PTFE inner tube also makes connection and servicing more difficult. It is also not possible using conventional methods to reinforce the PTFE inner tube with a helically wound wire. This is because the PTFE tubing resists bonding of a reinforcement wire to the tube.
Another problem with conventional PTFE potable water lines is the requirement that the potable water lines pass performance tests including repeated freezing. In order to pass these repeated freezing performance tests conventional PTFE hoses utilized especially thick PTFE inner tubes and, therefore, the tubing was unable to pass the small bend radius requirements. Still further, PTFE tubing which is reinforced with wire must be thicker in order not to be damaged during the repeated freezing tests and this also adds to the problem of bending and kinking. In summary, potable water lines constructed with a conventional PTFE inner tube have been comparatively rigid and easily kinked.
Still another problem with potable water tubing of the type used in commercial aircraft is the requirement that the tubing be able to be easily drained. This requires that the hose be sufficiently sturdy when freely resting on transverse supports spaced at a predetermined distance so as not to sag to create a captured pocket of water. This resistance to sagging conventionally required a PTFE tubing which was thicker and, therefore, less able to meet the requirements for small bend radius.
It is accordingly an object of the present invention to provide an improved hose with a polyfluorocarbon liner. More particularly, it is an object of the present invention to provide a kink-resistant, small bend radius hose with a polyfluorocarbon liner of the type suitable for use with potable water.
It is also an object of the present invention to provide a potable water hose with a polyfluorocarbon liner which has a small bend radius, is kink-resistant, is more resistant to sag, and which is capable of repeated freezing of the water therein without causing damage to the tube.